A new U.S. political survey signaled Sunday that Donald Trump, the front-runner for the Republican presidential nomination, is surging ahead in the crucial Midwestern state of Indiana, where party voters are holding the next nominating contest on Tuesday.

The NBC News/Wall Street Journal/Marist poll showed Trump with 49 percent support among Republicans in the state, compared to 34 percent for Texas Senator Ted Cruz, a conservative firebrand, and 13 percent for John Kasich, who governs the neighboring state of Ohio.

Last chance for Cruz, Kasich?

U.S. political analysts view the contest in Indiana, a politically conservative state with vast expanses of farmland and industrial centers, as possibly the last chance for Cruz or Kasich to stop Trump, a billionaire real estate mogul, from virtually clinching the Republican nomination.

Trump, a one-time television reality show host who has never held elective office, already holds a substantial lead over his challengers in the race to win a majority of delegates to July's Republican national convention where the party's nominee to run in November's national election will be picked.

Trump scored convincing wins in the last six state nominating contests, in his home state of New York and five nearby states in the northeastern U.S. He cannot clinch the nomination with a win in Indiana, but it would push him closer to securing it, with just nine states yet to vote in the next five weeks after Indiana, and, more importantly, continued momentum.

"If we win Indiana, it's over," Trump said this week as he campaigned in the state.

Cruz on Trump

Cruz acknowledged that he needs to halt Trump's march to the nomination, saying, "We're at the edge of a cliff and staring down."

Cruz, who delights in sparring with Democratic and Republican leaders alike in the halls of Congress in Washington, appeared on Sunday's news talk television shows to try to make the case that Trump and the leading Democratic contender, former U.S. Secretary of State Hillary Clinton, are both Washington insiders who would not be able to alter the capital's fractious political divide. Cruz called them both "New York liberals."

Cruz described Trump and Clinton "flip sides of the same coin. Behind the Donald Trump mask is Hillary Clinton," claiming that he supports many of the same policies she does.

Trump rebuffed the claim, saying, "Yes, I'm a conservative. But at this point, who cares? We've got to straighten out this country."

Cruz predicted that Clinton would easily defeat Trump in a hypothetical match-up in the November election, but declined to disavow support for him if he wins the Republican nomination.

Democratic camp

Clinton, the country's top diplomat from 2009 to 2013, is trying to become the country's first female president. She is significantly ahead of her sole challenger, Vermont Senator Bernie Sanders, in the contest for the Democratic nomination, but has yet to clinch a majority of the delegates to the party's July national convention.

Democratic U.S. presidential candidate and former U.S. Secretary of State Hillary Clinton arrives at the podium to speak to supporters during her five state primary night rally held in Philadelphia, Pennsylvania, April 26, 2016.

The NBC poll showed her with a 50-46 percent edge over Sanders in Indiana ahead of the Democratic primary there.

Clinton, the wife of former President Bill Clinton, told CNN she does not consider herself to be the party's presumptive nominee yet, but said she is "on the path" to claiming it.

The winner of the November election will succeed President Barack Obama when he leaves office in January.